The marine department of Qingdao, a coastal city in east China's Shandong Province, has started the building of artificial reefs and marine ranching in the Yellow Sea near Zhucha island since this April.

The artificial reef development is an important way to improve marine ecology and restore fishery resources. As of Tuesday, the ecological restoration project is about to come to an end.

The location and environment of artificial reefs need screening scientifically. According to the staff member of the project, not all sea areas are appropriate for artificial reefs.

"In fact most of the sea areas are not suitable for reef setting. We find that many parts of seabed are covered by a lay of thick silt. When artificial reefs land on the seabed, rocks would be swollen by mud, making little effect to our project. Reef needs a place to stand and form rock burst. The seabed should be rock face, or hard enough. If the location is covered by silt, the reef will sink in," said Liu Yuangang, a senior engineer of the Qingdao New West Coast Area Marine Development Bureau.

According to the expert, artificial reefs can provide habitats for algae and shellfishes, increase plankton, attract shrimps, crabs and fish and enrich living marine resources. At present, there are 21 marine pastures under construction in Qingdao, covering a total sea area of 11,360 hectares, and more than 3 million cubic meters of artificial reefs will be used.